1. Field of the Invention
The present invention relates to a resist coating and developing apparatus and a resist coating and developing method, which coats a resist onto a substrate and develops an exposed resist film to form a resist pattern. In particular, the present invention relates to a resist coating and developing apparatus, a resist coating and developing method, a resist-film processing apparatus, and a resist-film processing method, capable of reducing a line width roughness by planarizing the resist pattern.
2. Background of the Invention
In order to manufacture a semiconductor circuit having a higher integrity, further miniaturization is desired. For example, a critical dimension (CD) of an etching mask has reached 32 nm or 22 nm which is smaller than an exposure limitation of an existing exposure apparatus. In a case where a channel of such a width of a field-effect transistor (FET) is formed, if a line width roughness (LWR) of a resist pattern is large, voltage threshold values may become non-uniform, to thereby deteriorate properties as an integrated circuit and/or invite an abnormal operation.
In order to cope with these problems, there has been developed a method for processing a surface of a resist film by supplying a solvent gas to the resist film (Patent Document 1). According to this method, since the surface of the resist film is dissolved by the solvent gas, irregularities of the surface of the resist film are planarized, so that the LWR can be reduced.                Patent Document 1: JP2005-19969A        Patent Document 2: JP2002-359182A        
The method of Patent Document 1 has been examined in detail for further improvement, it was found that the resist dissolved by the solvent gas may deform a pattern shape of the resist film. To be specific, although the resist dissolved by a solvent has a viscosity, the resist is likely to swell and thus sag, so that a side surface of the resist film tend to incline. In other words, there is a possibility that, for example, a cross-sectional shape of a line part of the resist film might be a shape having a wide bottom instead of a rectangular shape. As a result, a line width may become broader than a desired line width and/or the pattern shape may deform because of a partial sagging. In this case, a desired shape cannot be transferred to a base layer, which impairs properties of a semiconductor device to be manufactured.